Simulated identification of silent COVID-19 infections among children and estimated future infection rates with vaccination

Importance: A significant proportion of COVID-19 transmission occurs silently during the pre-symptomatic and asymptomatic stages of infection. Children, while being important drivers of silent transmission, are not included in COVID-19 vaccination campaigns given their exclusion from clinical trials thus far. Objective: To investigate the impact of a targeted approach to identifying silent infections among children as a proxy for their vaccination. Design: This study used an age-structured disease transmission model to simulate the synergistic impact of interventions in reducing attack rates over the course of one year. Setting: A synthetic population representative of the demographics of the United States (US). Participants: Six age groups of 0-4, 5-10, 11-18, 19-49, 50-64, 65+ years old, stratified for their population size based on US census data. Exposures: Vaccination of adults, self-isolation of all symptomatic cases within 24 hours of symptom onset, and detection of silent infections. Main Outcomes and Measures: Vaccination of adults was implemented to reach a 40% coverage over the course of one year with a vaccine efficacy of 95% against symptomatic and severe COVID-19. Without vaccination of children, we determined the proportion and speed that would be required for identifying silent infections among this age group to suppress future attack rates below 5%. Results: A targeted approach that identifies 20.6% and 28.6% of silent infections among children within 2 or 3 days post-infection, respectively, would be required to bring attack rates under 5% with vaccination of adults. If silent infections among children remained undetected, achieving the same attack rates would require an unrealistically high vaccination coverage (at least 82%) of this age group, in addition to the base-case 40% vaccination coverage of adults. The results were robust in sensitivity analyses with respect to vaccine efficacy against infection and reduced susceptibility of children to infection. Conclusions and Relevance: In the absence of vaccine availability for children, a targeted approach to rapid identification of silent COVID-19 infections in this age group can significantly mitigate disease burden. Without measures to interrupt transmission chains from silent infections, vaccination of adults is unlikely to contain the outbreaks in the near term.